Finally, Some Answers on the Effects of Medicaid Expansion

Research suggests that access to care has greatly improved, and that quality of care has generally improved.

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Gov. Ralph Northam of Virginia, back to camera, got a hug from State Senator Emmett W. Hanger Jr. last month after signing state budget bills that included Medicaid expansion.CreditCreditBob Brown/Richmond Times-Dispatch, via Associated Press

When the Affordable Care Act first invited states to make more low-income people eligible for Medicaid, pretty much all the blue states said yes, but many red ones said no. Now, the Maine Legislature seems poised to overcome Gov. Paul LePage’s opposition to expanding the program. Just weeks ago, Virginia voted to expand Medicaid as well. They would join 32 states that have already expanded the program, and three others actively considering it.

But many are still arguing about whether the expansion actually provides adequate care for more Americans. Some believe it really doesn’t improve access to health care. Others believe that even if it does, it doesn’t improve the quality of that care.

Dozens of studies are starting to answer those questions, including a number in the June issue of the journal Health Affairs. Such studies can be useful to states that may want to jump into expansion, perhaps with their own conservative stamp. They may also prove useful to others that want to tinker with already existing programs to make things better in different areas.

Is Medicaid expansion helping rural areas?

Community health centers have long provided primary care to millions of patients in underserved areas across the United States, both urban and rural. Because most of their patients are poor or uninsured, they were expected to benefit from the Medicaid expansion. There was also hope that Obamacare’s increase in federal funding for such centers would lead to improvements in rural areas that have been difficult to reach.

Using data available each year from community health centers that receive federal funding,researchers explored how access and quality changed from 2011 to 2015, before and after the Medicaid expansion. They compared centers in states where expansion had taken place with those in states where it had not, and found that in the expansion states, the percentage of uninsured patients dropped more than 11 points. The percentage of patients covered by Medicaid increased by more than 13 points.

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Mainers for Health Care rallied outside the State House before Gov. Paul LePage’s State of the State address in February. The Maine Legislature seems poised to overcome the governor's opposition to expanding the program. CreditRobert F. Bukaty/Associated Press

Community health centers in urban areas where Medicaid expanded saw no significant changes in quality compared with those in urban areas in nonexpansion states. But rural health centers in states that expandedexperienced significant gains. More patients with asthma received appropriate drug treatment (4 percent more), more patients received appropriate weight screening and follow-up (7 percent more), and more patients with hypertension gained control over their blood pressure (2 percent more). Gains among rural Hispanic patients were even larger than those among white patients.

Some of these gains might be because pharmaceutical treatment became much more affordable with Medicaid. More of these gains, however, may be because insurance access makes visits to health professionals easier. Extrapolated to the whole population, the Medicaid expansion appears to have resulted in about 427,000 extra visits for depression and 457,000 extra visits for high blood pressure in rural health centers alone.

These visits and improvements are occurring in areas of the country that tend to be underserved and hard to affect. The visits could also be substantially increased if holdout states expanded Medicaid.

Do more conservative versions of Medicaid work?

Indiana expanded Medicaid through a waiver process, creating the Healthy Indiana Plan 2.0. Enrollees must make contributions to a health savings account, on a sliding scale based on income, to qualify for full benefits. If enrollees miss a payment, they receive reduced benefits. If they earn more than the poverty line and miss a payment, they can be locked out of coverage for half a year.

Many experts (including me) feared that Indiana would, consequently, see less benefit from the Medicaid expansion. These concerns have national implications: Other states are trying to expand Medicaid in novel ways, encouraged by Seema Verma, one of the architects of Healthy Indiana Plan 2.0 and current head of the Centers for Medicare and Medicaid Services.

Researchers from Indiana University’s School of Public and Environmental Affairspublished a paper to see how Indiana had fared compared with other expansion states. They used data from the American Community Survey, which gathers information on three million people across the United States each year. Specifically, they looked at whether adults 18 to 64 (who might be affected by the expansion) had Medicaid or other insurance from 2009 through 2016.

All states that expanded Medicaid saw greater gains in coverage than those that did not. Indiana ranked in the middle, 13th of 27 states. In general, states with higher uninsurance rates before expansion saw larger gains, and Indiana ranked in the middle before and after expansion.

The good news is that even with these extra requirements, Indiana saw significant gains in Medicaid coverage. But we don’t know if gains would have been even larger without them. It’s possible that the churn caused by cost-sharing requirements may be causing the state to underperform. Neighboring states did see larger gains than Indiana itself. But Indiana overperformed compared with other, more distant states, making this unclear.

What’s the big picture?

These are individual studies. Looking at all the research together might provide a more accurate picture of how the Medicaid expansion is performing. Another study in Health Affairs by Indiana University health services researchers (I was one of them) systematically reviewed the literature to gather all available peer-reviewed evidence.

Since the start of Medicaid expansion, 77 studies, most of them quasi-experimental in design, have been published. They include 440 distinct analyses. More than 60 percent of them found a significant effect of the Medicaid expansion that was consistent with the goals of the Affordable Care Act.

Only 4 percent reported findings that showed the Medicaid expansion had a negative effect, and 35 percent reported no significant findings. Negative effects could include more uninsurance and increased wait times, but none showed decreased quality. It should be noted, moreover, that the few studies with negative outcomes were more likely to employ methodologies that were less likely to be able to show that Medicaid was causing these outcomes.

The majority of analyses looked at access to care, and they showed that after the Medicaid expansion, insurance coverage improved and the use of health services increased. It’s harder to study quality than access, but 40 analyses in 16 studies did so. About half of these reported improvements in quality measures like diabetes monitoring or preventive care screenings.

It has only been a few years since the Medicaid expansion, and clearly we need to follow these results over time. But the evidence to date is — if anything — positive. As Olena Mazurenko, the lead author of the systematic review, wrote to me, “With dozens of scientific analyses spanning multiple years, the best evidence we currently have suggests that Medicaid expansion greatly improved access to care, generally improved quality of care, and to a lesser degree, positively affected people’s health.”

States should keep this in mind as they debate whether and how to accept the A.C.A.’s invitation to expand Medicaid.

A version of this article appears in print on , on Page A13 of the New York edition with the headline: Finally, Some Answers on Effects of Medicaid Expansion. Order Reprints | Today’s Paper | Subscribe